Wireless localization method based on an efficient multilateration algorithm over a wireless sensor network and a recording medium in which a program for the method is recorded

Abstract

A wireless localization technology using efficient multilateration in a wireless sensor network is disclosed. After calculating estimated distances from each of at least three reference nodes to a blind node using received signal strength of wireless signals that the at least three reference nodes received from the blind node, the estimated location of the blind node is obtained through multilateration using the calculated estimated distances. To correct error in the estimated location, the estimated distances are used, and the error correction direction and error correction distance for the estimated location are calculated by applying a largest weight to the reference node closest to the estimated location. The error of the estimated location is corrected by move the estimated location of the blind node by the calculated error correction direction and error correction distance. Calculation for the error correction is very simple and fast.

Description

BACKGROUND OF THE INVENTION[0001]1. Field of the Invention[0002]The present invention relates to a wireless localization method based on a wireless sensor network, more specifically to a wireless localization method, which is able to correct localization error precisely in real time in a wireless localization through multilateration algorithm using received signal strength indicator (RSSI). Here, the term ‘multilateration’ is a concept including trilateralism and indicates a method for estimating an estimated location of a blind node using more than three reference nodes.[0003]2. Background Art[0004]As the interest on smart phones increases explosively, a location based service (LBS) receives spotlight, and for example, location-recognizing applications such as augmented reality, medical care, home network, monitoring applications, etc. are popular. For such a LBS, a localization on location of user requesting the service must be achieved precisely.[0005]A well-known localization sy...

AI Technical Summary

Benefits of technology

[0022]According to the present invention, in a wireless localization using multilateration, the accuracy of estimated location of blind node can be improved much by finding out an estimated distance including relatively large estimation error and then reducing the error in the estimated distance.

[0023]In the conventional WLSE's estimation algorithm, a weight could be applied only if knowing a random factor and a channel exponent precisely and calculations must be repeated for error correction of estimated location. In contrast, idea of the present invention is simple due to a few operations but powerful algorithm, which makes it easy to implement. Since the present invention enables correction of location just by comparing estimated distances from each reference node to blind node, the calculation for location estimation is very simple and can be performed effectively. Therefore, the wireless localization method according to the present invention can be a very efficient method for real-time positioning or locating.

[0024]The present invention provides better accuracy in localization also with all numbers of nodes. Especially, drastic improvement can be obtained than conventional methods when using the fewest three nodes.

Problems solved by technology

However, the GPS provides a high performance in an outdoor environment, but since the location information is obtained using satellites there is a limit in that it is hard to achieve a precise localization indoors.

Therefore, the GPS is not suitable for a localization system in indoor channel environments or with low-cost devices.

A method for estimating a location without information on the distance between transmitter side and receiver side in estimating the location of a user is the range free approach, but since the method requires a high cost and has to store enormous amount of information, its real feasibility is low.

However, if there is a large error in estimating the distance between transmitter side and receiver side, the distance is estimated too large or too small, such that one circle may be separated from the other circle(s) or one circle may include the other circle(s) completely, that is, an occasion that the three circles are not able to form cross lines (see FIG. 3) may occur in real situation.

However, since such conventional wireless localization method based on error-correction of estimated distance has an algorithm of complicated and recursive calculations and the amount of calculations increases further to increase accuracy of localization, it is not suitable to the real-time wireless localization service.

For it is very hard to know precisely two channel factors.

Therefore, it does not become a practical method.

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